In a method and an apparatus known from US 2005/0168851 A1 for imaging a radiation-sensitive substrate, a programmable template is illuminated with coherent radiation and projected by means of an optical system onto the substrate that is sensitive to the radiation used. The coherent radiation is split by means of two Bragg cells into a plurality of first and higher-order beamlets and is supplied to the programmable template via a collection lens. The beam bundles radiated from the template are successively directed onto the substrate by means of a scanner, wherein the specific beam bundle and furthermore the substrate are displaced. The programmable template may be a controllable micro-mirror array, for instance, the individual elements of which are embodied spatially separated from one anther. The optical system, constructed from at least two independent groups of lenses, produces an appropriate scaled image on the substrate by overlaying the individual images for each individual element.
Furthermore, known from US 2006/0176 323 A1 are a method and an apparatus having a light source, the diverging beam bundle of which is directed onto a programmable template via a collection lens. There is no expansion of a coherent beam bundle. The output radiation of the programmable template travels onto a movable lens to which linear actuators are allocated. The angle of incidence of the striking beams is changed, and thus the image position is changed, corresponding to the movement of the movable lens. In another exemplary embodiment the change in the image may be brought about by modulation of the optical properties of a plate using integrated optical systems or various electro-optical modulators or acoustic-optical modulators.
Undesired interference effects result from the nature of coherent radiation, especially when the resolution of the optical system is too low, and these interference effects have a negative impact on the quality of the structures produced. At high resolution there is slight overlaying of the individual images so that the interference effects are negligible. However, using this slight overlapping it is not possible to attain a displacement of the structure edges on the substrate by varying the radiation intensity of adjacent individual images. A mechanical method that requires a plurality of exposure processes is described in document DE 10 2008 017 623 A1.
Known from document U.S. Pat. No. 4,541,712 is an apparatus for producing a laser pattern in which a plurality of laser light sources are densely arranged in a non-interfering field. The emitted laser light beams are scanned simultaneously over a region of a target surface by means of an acoustic-optical deflector. After one working cycle, the target surface is moved perpendicular to the scanning direction in order to reposition for the next working cycle.
U.S. Pat. No. 6,552,779 B2 describes a maskless exposure system for digital photolithography. A field of mirrors can be controlled digitally such that a light pattern results in the light reflected by the mirrors. The reflected light pattern is projected by means of a first f-θ lens system onto a rotary mirror that scans the light pattern over an object surface using a second f-θ lens system.